Trace Element Chemistry, Heavy Minerals, and Sediment Statistics Of Weddell Sea Sediments

Abstract

Chemically, the sediments from the Weddell Sea differ from the sediments of the Amundsen, Bellingshausen, and Ross Seas. As a group, they have a similar concentration of Cr, Ni, Al, and Co, but the Weddell Sea sediments are considerably lower in Mn, Fe, Ti, V, and Cu. When compared to crustal abundance figures, they are lower in Mg, Ni, Mn, Fe, Al, and Ti; higher in Zr, B, V, and Cu; and similar in content in Cr and Co. The Mn/Fe, Mn/Ti, Mn/Al, Ni/Al, and Fe/Al ratios show great differences between glacial marine and normal deep sea sediments. Somewhat less but still useful differences exist between V/Al and Co/Al ratios. Ternary diagram plots of V, Cu, and Co+Ni content delineate distinct fields for glacial marine, pelagic, and shallow water sediments. For pelagic vs. glacial marine sediments a ternary plot of Al, Fe, and Mn+Ti shows a restriction of glacial marine sediments to a narrow field along the Al-Fe join. As is well known, the type of sediment surrounding Antarctica and which is found in the Weddell Sea area is distinctive among marine sediments. These deposits have the mechanical characteristics of tills. The poor sorting is unusual for marine deposits. Marine currents have had little or no sorting effort on these sediments. Major characteristics of these sediments are the freshness and angularity of the detrital material. The heavy minerals indicate that the Weddell Sea sediments are derived predominately from an area of metamorphic rocks and transported and(or) rafted across the area of the Filchner Ice Shelf by floating ice. This mode of transport is indicated by the polymodal size distribution of the sediments.